Alphabet Inc.’s (GOOG) Google and its Chromebook may still be the leader in the U.S. education market, but internationally Microsoft Corp. (MSFT) is gaining a lot of ground.

For the third quarter, Futuresource Consulting, a market research and consultancy firm, found that outside the U.S., the use of technology in the classroom is becoming more common, driving demand for Microsoft’s education notebooks and operating system. During the third quarter, the research firm found the mobile PC education market grew 26% internationally with Microsoft's OS the dominant one. The Redmond, Wash., technology giant has been benefiting overseas from big emerging-market deals that boosted its market share. (See also: Why Google Chromebooks Are a Hit in Schools.)

In the U.S., Google is still the undisputed leader in education, but it is in a market that is starting to show signs of maturity. According to Futuresource, the mobile PC education market saw several years of double-digit growth, but in the third quarter of this year was up just 3.5% year-over-year. For all of 2017, the research firm is forecasting growth of only 9%. Last year it lodged annual growth of 19%. What’s more, by the end of the year the penetration of mobile PCs will have reached 50%, with a growing portion of the future sales becoming replacement sales. Against that backdrop, competition between Google, Microsoft and Apple Inc. (AAPL) is becoming much fiercer. In May, Microsoft announced a new Surface Laptop and Windows 10S operating system geared toward the education market.

Time for an Upgrade?

The Windows 10 S operating system is streamlined for classroom use, and it’s directly aimed at stealing market share from Google’s Chrome operating system, which powers bare-bones low-cost Chromebook laptops. The new OS enables people to only run applications that are downloaded from the Microsoft’s Windows Store. (See also: Microsoft Targets Ed. Market With New Surface, OS.)

Even though Google is still winning in the U.S., Futuresource said there are signs that its growth rate is slowing at the same time Microsoft is gaining market share. With many Chromebooks that were deployed in the 2014-15 school year soon in a need of an upgrade, it remains to be seen if educators will stick with Google or switch to Microsoft or Apple.

“Microsoft has made huge strides in developing its education ecosystem offering in the past year, with major announcements on both the devices and platform side. Q3 2017 was the first time we saw and heard about a slight shifting of the competitive scenario in the US, with many OEMs and major channel players reporting faster growth (and expected growth) on Windows than Chrome based devices,” wrote Mike Fisher, associate director at Futuresource Consulting, in a research report. “The challenge now for Microsoft will be how to accelerate this trend in 2018. The majority of market demand is expected to be replacement demand; convincing existing Chrome users to completely change the existing ecosystem will likely not be easy due to the time and cost involved.”